In display systems, such as digital light processor (DLP) systems and liquid crystal display (LCD) systems, it is often desirable to include information in displayed images that is usable by the display system or another electronic device for geometric calibration or other purposes. With many display systems, however, information that is included into displayed images may be seen by a viewer. The information may detract from the viewer's enjoyment of the displayed images. It would be desirable to be able to include information in visual images formed by a display system where the information is at least substantially imperceptible by a viewer.